NOTES: Calls are by oceangoing vessels of 10,000
dwt or greater at U.S. ports, excluding Great Lakes ports. 1998 is the first year for which data are
available. Beginning in 2002, chemical
tanker data are no longer reported separately and are, instead, included in
tanker data; historical data were adjusted for consistency. Combination includes ore/bulk/oil carriers, and bulk/oil carriers. Gas carriers includes
liquified natural gas carriers (LNG), liquified petroleum gas (LPG) carriers
, and LNG/LPG carriers. General cargo includes general cargo carriers, partial containerships,
refrigerated ships, barge carriers, and livestock carriers. Roll-on,
roll-off vessels are especially designed to
carry wheeled container trailers or other wheeled cargo and use the roll-on,
roll-off method for loading and unloading.